path: root/http.cpp

#include "http.h"

#include "server.h"
#include "response.h"

#include <boost/beast/version.hpp>
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/dispatch.hpp>
#include <boost/asio/strand.hpp>
#include <boost/config.hpp>
#include <algorithm>
#include <cstdlib>
#include <functional>
#include <iostream>
#include <memory>
#include <string>
#include <thread>
#include <vector>

namespace beast = boost::beast;         // from <boost/beast.hpp>
namespace http = beast::http;           // from <boost/beast/http.hpp>
namespace net = boost::asio;            // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>

namespace {

// This function produces an HTTP response for the given
// request. The type of the response object depends on the
// contents of the request, so the interface requires the
// caller to pass a generic lambda for receiving the response.
template<class Send>
void
handle_request(
    ::Server& server,
    request_type&& req,
    Send&& send)
{
    return send(std::move(generate_response(req, server)));
}

//------------------------------------------------------------------------------

// Report a failure
void
fail(beast::error_code ec, char const* what)
{
    std::cerr << what << ": " << ec.message() << "\n";
}

// Handles an HTTP server connection
class session : public std::enable_shared_from_this<session>
{
    // This is the C++11 equivalent of a generic lambda.
    // The function object is used to send an HTTP message.
    struct send_lambda
    {
        session& self_;

        explicit
        send_lambda(session& self)
            : self_(self)
        {
        }

        template<bool isRequest, class Body, class Fields>
        void
        operator()(http::message<isRequest, Body, Fields>&& msg) const
        {
            // The lifetime of the message has to extend
            // for the duration of the async operation so
            // we use a shared_ptr to manage it.
            auto sp = std::make_shared<
                http::message<isRequest, Body, Fields>>(std::move(msg));

            // Store a type-erased version of the shared
            // pointer in the class to keep it alive.
            self_.res_ = sp;

            // Write the response
            http::async_write(
                self_.stream_,
                *sp,
                beast::bind_front_handler(
                    &session::on_write,
                    self_.shared_from_this(),
                    sp->need_eof()));
        }
    };

    beast::tcp_stream stream_;
    beast::flat_buffer buffer_;
    Server& m_server;
    http::request<http::string_body> req_;
    std::shared_ptr<void> res_;
    send_lambda lambda_;

public:
    // Take ownership of the stream
    session(
        tcp::socket&& socket,
        Server& server)
        : stream_(std::move(socket))
        , m_server(server)
        , lambda_(*this)
    {
    }

    // Start the asynchronous operation
    void
    run()
    {
        // We need to be executing within a strand to perform async operations
        // on the I/O objects in this session. Although not strictly necessary
        // for single-threaded contexts, this example code is written to be
        // thread-safe by default.
        net::dispatch(stream_.get_executor(),
                      beast::bind_front_handler(
                          &session::do_read,
                          shared_from_this()));
    }

    void
    do_read()
    {
        // Make the request empty before reading,
        // otherwise the operation behavior is undefined.
        req_ = {};

        // Set the timeout.
        stream_.expires_after(std::chrono::seconds(30));

        // Read a request
        http::async_read(stream_, buffer_, req_,
            beast::bind_front_handler(
                &session::on_read,
                shared_from_this()));
    }

    void
    on_read(
        beast::error_code ec,
        std::size_t bytes_transferred)
    {
        boost::ignore_unused(bytes_transferred);

        // This means they closed the connection
        if(ec == http::error::end_of_stream)
            return do_close();

        if(ec)
            return fail(ec, "read");

        // Send the response
        handle_request(m_server, std::move(req_), lambda_);
    }

    void
    on_write(
        bool close,
        beast::error_code ec,
        std::size_t bytes_transferred)
    {
        boost::ignore_unused(bytes_transferred);

        if(ec)
            return fail(ec, "write");

        if(close)
        {
            // This means we should close the connection, usually because
            // the response indicated the "Connection: close" semantic.
            return do_close();
        }

        // We're done with the response so delete it
        res_ = nullptr;

        // Read another request
        do_read();
    }

    void
    do_close()
    {
        // Send a TCP shutdown
        beast::error_code ec;
        stream_.socket().shutdown(tcp::socket::shutdown_send, ec);

        // At this point the connection is closed gracefully
    }
};

//------------------------------------------------------------------------------

// Accepts incoming connections and launches the sessions
class listener : public std::enable_shared_from_this<listener>
{
    net::io_context& ioc_;
    tcp::acceptor acceptor_;
    Server& m_server;

public:
    listener(
        net::io_context& ioc,
        tcp::endpoint endpoint,
        Server& server)
        : ioc_(ioc)
        , acceptor_(net::make_strand(ioc))
        , m_server(server)
    {
        beast::error_code ec;

        // Open the acceptor
        acceptor_.open(endpoint.protocol(), ec);
        if(ec)
        {
            fail(ec, "open");
            return;
        }

        // Allow address reuse
        acceptor_.set_option(net::socket_base::reuse_address(true), ec);
        if(ec)
        {
            fail(ec, "set_option");
            return;
        }

        // Bind to the server address
        acceptor_.bind(endpoint, ec);
        if(ec)
        {
            fail(ec, "bind");
            return;
        }

        // Start listening for connections
        acceptor_.listen(
            net::socket_base::max_listen_connections, ec);
        if(ec)
        {
            fail(ec, "listen");
            return;
        }
    }

    // Start accepting incoming connections
    void
    run()
    {
        do_accept();
    }

private:
    void
    do_accept()
    {
        // The new connection gets its own strand
        acceptor_.async_accept(
            net::make_strand(ioc_),
            beast::bind_front_handler(
                &listener::on_accept,
                shared_from_this()));
    }

    void
    on_accept(beast::error_code ec, tcp::socket socket)
    {
        if(ec)
        {
            fail(ec, "accept");
        }
        else
        {
            // Create the session and run it
            std::make_shared<session>(
                std::move(socket),
                m_server)->run();
        }

        // Accept another connection
        do_accept();
    }
};

} // anonymous namespace

//------------------------------------------------------------------------------

namespace HTTP {

 Server::Server(Config& config, boost::asio::io_context& ioc, const Socket& socket, plugins_container_type& plugins)
  : ::Server(config, ioc, socket, plugins)
 {
 }

 Server::~Server()
 {
 }

 int Server::start()
 {
  auto const address = net::ip::make_address(m_socket.address);
  auto const port = static_cast<unsigned short>(std::atoi(m_socket.port.data()));

  // Create and launch a listening port
  std::make_shared<listener>(
   m_ioc,
   tcp::endpoint{address, port},
   *this)->run();

  return EXIT_SUCCESS;
 }

} // namespace HTTP